1. Field
Embodiments of the present invention relate to an image forming apparatus which performs a stable paper feeding operation.
2. Description of the Related Art
An image forming apparatus is an apparatus for printing an image on a printing medium, and includes printers, copiers, facsimiles and all-in-devices in which functions thereof are integrated.
An image forming apparatus adopting an electrophotography method scans light on a photoreceptor charged with a predetermined potential, forms an electrostatic latent image on a surface of the photoreceptor, and then supplies a toner to the electrostatic latent image to form a visible image. The visible image formed on the photoreceptor is directly transferred to a printing medium or is transferred to the printing medium via an intermediate transfer body, and the visible image transferred to the printing medium is fixed to the printing medium while passing through a fixing unit.
The image forming apparatus may include a paper pick-up unit for picking up paper loaded in a cassette or a tray one sheet at a time, and a paper feeder for conveying the picked-up paper to a paper conveying route provided inside the image forming apparatus. Two or more sheets of paper may sometimes be picked-up at one time due to a frictional force of the paper or the like and be conveyed to the paper conveying route by the paper pick-up unit to then be conveyed to an inside of the paper conveying route. In the image forming apparatus, a jam due to double feeding the paper may occur, and various other problems may also occur.
Recently, a retarding pick-up structure, in which a torque limiter and a retard roller connected to the torque limiter to be rotated in a normal or reverse direction according to the torque limiter are used, is provided to prevent a double feed of paper. The torque limiter has a predetermined critical torque value, is rotated in the normal direction when a paper conveying frictional force is greater than the critical torque value, and is rotated in the reverse direction when the paper conveying frictional force is less than the critical torque value. The retard roller is installed at a lower side of the paper conveying route and prevents a double feed of paper.